1. Field of the Invention
The present invention relates to a magnetic material suitable for antenna use, as well as to an antenna and a wireless communication device using the same.
2. Description of Related Art
In recent years, wireless signal frequencies used in wireless communication devices such as portable telephones and personal digital assistants have been increasing to a higher frequency band. For example, in portable telephones of the first generation, the frequencies being used were in the 800 MHz band, whereas in portable telephones of the third generation which began to be available in 2001, the frequencies being used are in the 2 GHz band, and an antenna that could be used in the GHz band is needed, including the use of GPS, Bluetooth and wireless LAN. Along with the addition of the multiple functions of the wireless communication devices, a multi-band/mode corresponding to a plurality of wireless systems has been developed, and an antenna used for such wireless communication devices needs to be available in a wide frequency band. Recently, along with a size reduction of the wireless communication device, a further size reduction of the antenna itself has also become an urgent issue. Therefore, for recent antennas used for wireless communication devices, a widening of the bandwidth in high frequencies and a size reduction are both desired.
Regarding this technique, for example, patent document 1 discloses a chip antenna element of a microstrip structure for the purpose of size reduction, higher gain and obtaining wide bandwidth characteristics by appropriately selecting the shapes of emitting electrodes and ground electrodes. Patent document 2 discloses a hexagonal ferrite containing a Y-type ferrite as the main phase and an antenna using the same. Patent document 3 proposes an antenna using, as an electromagnetic bond adjustor, a nano composite magnetic dielectric material in which superparamagnetic nano particles are dispersed in a non-magnetic matrix. Patent document 4 discloses a composite magnetic material formed by a magnetic oxide, having Co substitutional W-type hexagonal ferrite as the main phase, dispersed in the resin and an antenna using the same. Patent document 5 discloses an antenna apparatus comprising an insulator layer made of an oxide magnetic material comprising a Y-type, a Z-type or a M-type ferrite compound.